#!/usr/bin/perl -l

use strict;
use warnings;
use Data::Dumper;

sub ndim {
    my ($n,$m) = @_;
    return [(1) x $m] if $n==1;
    [map [@{ ndim($n-1,$m) }], 1..$m];
}

$Data::Dumper::Indent=0;
print Dumper ndim @$_ for [1,3], [2,2], [2,3], [3,3];

__END__
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Of course this is much ref-deref madness so I would probably use a helper sub instead, at the expense of some extra verbosity:

sub _ndim {
    my ($n,$m) = @_;
    return (1) x $m if $n==1;
    map [_ndim($n-1,$m)], 1..$m;
}

sub ndim { [_ndim @_] }
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(Incidentally, how tempted I would be to put _ndim inside ndim... if only it were not for the "Variable "%s" will not stay shared" gotcha - and yes, I'm aware of the ways round... most of all I'd like lexical named subs, though!)